Directions

In a bowl, combine the olive oil, piment d'Espelette, salt and tuna.
Stir well to coat all of the pieces of fish; cover the bowl, and
refrigerate.

In a 4- or 5-quart slow cooker, add the onion, garlic, black pepper,
wine, diced tomatoes, potatoes and chicken stock. Cook on HIGH for 2
hours, or on LOW for 4 hours.

Add the bell peppers, and cook on HIGH for 1 hour.

Then, add the tuna and all of the marinade to the slow cooker. Cook on HIGH for 30 minutes.

Use a slotted spoon to remove all of the fish and vegetables from the
slow cooker; place in a large mixing bowl. Pour the liquid from the
slow cooker into a small sauce pan, and set over high heat on the stove
top.

In a small glass measuring cup, stir together the arrowroot with 3
tablespoons of water. Pour this slurry into the liquid in the sauce pan,
and stir to ensure no lumps form. When the liquid has thickened
slightly, pour it over the fish and vegetables.

Serve hot, over white rice, or let the dish cool completely, and refrigerate for up to 3 days.